An inductor is an important component for an electric circuit with a resistor, a capacitor, a transistor and a power source. The inductor has a coil structure where a conductor is wound many times as a screw or spiral form, as an example. The inductor suppresses a rapid change of a current by inducing voltage in proportion to an amount of a current change. A ratio of counter electromotive force generated due to electromagnetic induction according to the change of the current flowing in a circuit is called an inductance (L).
Generally, the inductor is used in an Integrated Circuit (IC) for communication systems including high performance RF filters, and distributed amplifiers. In particular, inductors are used in a packaging technology for integrating many elements to a single chip, known as a System on Chip (SoC). Accordingly, an inductor having a micro-structure and good electrical characteristics is needed.
A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Commonly, transformers are used to increase or decrease the voltages of alternating current in electric power applications. For example, in operation, a varying current in the transformer's primary winding creates a varying magnetic flux in the transformer core and a varying magnetic field impinging on the transformer's secondary winding. This varying magnetic field at the secondary winding induces a varying electromotive force (EMF) or voltage in the secondary winding due to electromagnetic induction. However, very high turns ratio transformers are planar with limited coupling with a large area footprint, which increases manufacturing costs. In addition, existing high turns ratio transformers have reduced current handling capability.